Stanislaus County is a county located in the Central Valley of the U.S. state of California. As the price of housing has increased in the San Francisco Bay Area, many people who work in the southern reaches of the Bay Area have opted for the longer commute and moved to Stanislaus County for the relatively affordable housing.

As of 2000 the population was 446,997. Per 2008 US Census Estimates, that number has grown to 510,694. The county seat is Modesto. Stanislaus County is included in the Modesto Metropolitan Statistical Area. Estanislao was his baptismal name, the Spanish rendition of Stanislaus, itself the Latin rendition of the name of an 11th century Catholic Saint Stanislaus the Martyr.